A safety device for vehicle occupants is shown in DE-A-28 51 333. A device for storing electrical energy is provided for safety reasons. Electrically actuated tripping devices actuate the safety device if, for example, the connection to the main source of energy of the vehicle, typically the vehicle battery, is interrupted.
Ignition tablets, which are electrically actuated, are frequently used as tripping devices. The electric current flowing through an ignition tablet generates heat which, in turn, initiates a pyrotechnical reaction. One problem with ignition tablets, however, is that after ignition occurs, they are prone to shunts. A shunt can drain the limited energy reserve of the storage device. As a result, the amount of available energy is frequently insufficient to actuate additional tripping devices necessary to successively trip corresponding inertial restraining devices.
German Patent Application P 37 29 785.6 suggests measuring the energy supplied to a tripping device after it is actuated with an evaluating device, and then interrupting the energy supply to that tripping device if a specified energy limit value is reached. However, if the storage device for electrical energy is defective, the evaluating device can incorrectly calculate the available energy of the storage device. As a result, the evaluating device can interrupt the flow of electric current to the ignition tablet before it is ignited.